100 Amp Alternator

[sailaway78]

For those of you who have the big 100 amp or so alternators installed on your boat I have a question. How do you drive it. If you use a single belt, do you have a problem with belt slippage, or belt life. I want to install a larger alternator than the stock 35 amp Hitachi on a Yanmar 3GM, single belt drive. But wonder how big I can go without having a problem with belt slippage and short belt life. I have always been led to believe that 100 amps is at or beyond the capacity of a single belt drive. Also believe that a super tight belt is hard on water pump bearings. What are your results, and problems. The choices I have are 60, 90 or 100 amp. Leaning towards the 60amp. because of the drive worry, but would prefer to use 90 or 100. There is a company that has a 90 amp Hitachi, made for the Yanmar for 135 bucks, that I would like to use.

 

[Don S/V ILLusion]

Before going to the extreme of installing a 100 amp alternator on a small diesel, have you considered the regulator as the limiting factor?
The difference in alternator rating (between 60 and 100 amps) is not that obvious in terms of actual charge rate which is almost entirely dependent upon what regulator you have and how it is set. I'm assuming you have also considered this in the context of the entire system - alternator, regulator and battery bank size, all of which have equal bearing on the selection of any one component.

A 60 amp alternator with a good 3 stage regulator can produce sufficient bulk charging to properly care for a 250 amp bank.

Other considerations include larger alternators require more power to drive them, more cooling to preserve them and more money to buy them.

 

[ScottyIrwin]

Also keep in mind that 100 amps requires 1.6 hp to run it. (100amps * 12 volts = 1200 watts = 1.6hp) I ran into this problem on my ODay 30 with a YSB 12 engine.

 

[Lee Coller]

I have a 100 amp Balmar on my Yanmar 4JH3E (56HP) using 1 belt. I've had no problems with slippage. Balmar says you don't need 2 belts until you get to 110 amps.

 

[Eric M]

I have a 90 amp Balmar alternator on my Yanmar 3HM30, also a single belt drive. The alternator was installed by the previous owner and he and I have had chronic premature belt wear out issues. I get ~100 engine hours out of a belt. I cannot say for certain that the alternator is the culprit but I can say it is the only part of the system that is not the original design from Yanmar.

 

[larryw]

I have a 115 A Balmar on a single belt, charging a 450AH bank thru a Link 2000. I have no problems with belt slippage, wear, or engine bogging, but the engine is a 50hp Perkins. Make absolutely certain the pulleys all align. A misaligned pulley will literally shred belts. Instead of buying a new alternator, take yours to a place that specializes in large alternators. Mine but was rebuilt and beefed up by a local truck electric place for about a quarter of what a new one would have cost, and they can tailor it for whatever regulator you want to use.

 

[Hermit Scott]

ScottyIrwin did you

install the 100 amp on the YSB 12? What alternator did you end up putting on it? I have a YSM 12 w/ a 35 amp. I want to have a bigger alternator but I don't think I can afford the horses.

 

[ScottyIrwin]

install the 100 amp on the YSB 12? What alternator did you end up putting on it? I have a SM 12 w/ a 35 amp. I want to have a bigger alternator but I don't think I can afford the horses.

I ended up putting a GM 10Si 60 amp alternator on it with a custom bracket. I can take some pics of it and email them to you if you want. I never had trouble running that alternator, but as a safety net I put a toggle switch on the exciter wire on the alternator (white wire on a standard GM alternator) so I could turn off the alternator at low engine speed. I would turn on the engine with the switch off and bring it up to cruising speed (I used to run that motor at about 2200 ~ 2500RPM) and then turn on the alternator switch. This way the engine was making max HP before I put the load of the alternator on it. Also remember that when using a regular "automotive" style regulator if your batteries are not dead and do not require 60 amps, your alternator will not put out that much, so in other words if you don't run them down low you won't be using the full 60 amps. I had 2 6 volt batteries in series on the ODay and I could run as much as I wanted at night and have no trouble recharging them. With the 60 amp alternator I never used the switch, I only did with my 85 amp alternator and a dead house bank...I can still smell the belt haha...

****EDIT**** I had thuis setup with a 1:2 pully ratio on the alternator so it spun up to 4400 to 5000 RPM.

 

[Stu Jackson]

Larger Alternator Operation

1. Very good question. Here's a link to a long discussion on our C34 Message Board. http://c34.org/bbs/index.php?topic=4454.0

2. Belt tension is belt tension, not too tight, 90 degree twist and 1/2 inch deflection.

3. I'm still using the single 3/8 belt.

4. It slips a bit when the engine is run full out after a heavy discharge. It's the nature of the beast. How do I know this? The tach is about 2/3rds of its normal operating range.

5. So, either turn down the amp manager on the regulator, or run the engine slower until the bulk charge has finished (i.e., amperage reduced from acceptance rate of the bank).

We have a 100 A alternator with a Balmar MC-612 Max Charge regulator on an M25 Universal (Kubota) engine.

 

[sailaway78]

More info

Have recently replaced the house bank, going from two group 39's to four 6volt golf cart batteries. The house bank is 450 ah. Want to add refrigeration is the reason for upgrading the battery/alternator system. After reading the replies, am leaning more towards a 60 amp alternator, with smart regulator. I think I can find a direct replacement for the 35 amp Hitachi, from auto supply store, and not put out the big bucks for the high end marine stuff. Hell, my local Auto Zone/Napa/O'Reilies offers lifetime warranties on thier alternators, much lower price and easy to find almost anywhere. Which regulators do most of you use. I have read of several Balmar failures, and they are certainly high buck items.

 

[sailaway78]

Should have read

A slight slip between the brain and the fingers. That should have read two group 29's, not 39's. It's hell getting old.

 

[alexco38]

Got an auto-electrical shop to get me a rebuilt 90 amp from a GM diesel truck. The auto-electrical shop tab out a techchonmeter wire. The belt was replaced with a cogged belt for flexibility. Make sure you have absolute pulley alignment.

 

[Stu Jackson]

Go to Maine Sail's 'site (click his link from any of his posts) - he used a Leece Neville regulator with internal regulation, saved on buying an external regulator. Xantrex makes them, too. probably the same circuit board, though. Our Balmar is working fine, two years.

 

[ScottyIrwin]

I have had really good luck just using the internal regulator on the automotive alternator (GM 10si internally regulated)

I know I'm asking for trouble stating that...

 

[kloudie1]

Excellent advice across the board.. Heat is a big enemy of installations like this is gonna be .. I also believe that an auto unit that has been fixed to accept the smart regulator is the way to go. If the shop has a bigger fan that will fit, it would be a good thing to have.
I don’t have experience with this exactly but 90 amperes at 13.5 V or so and around 80% alternator efficiency means it will consume about 2 horsepower.. max... Should be no problem for a well aligned and tensioned single belt drive. Alignment will be critical to have exactly right, as has already been mentioned.. Good Luck with it!. Two horsepower is about what a normal lawn edger does through its single belt drive when loaded..

 

[RAD]

Arco 105 amp alternator

A few years ago I stumbled upon a company in Florida that supply's alternators and I bought at a reasonable price a 105 amp,low rpm,external voltage adjustment,single pulley alternator and it works well.
I would think problems with belts and slippage when the alternator is on its knees trying to put out 105 amps

http://www.arcomarine.com/xhtml/Pages 52-59 Alternators.pdf

 

[Joseph Shirley]

I have an Ample power 124 Amp Small Frame Alternator on my Yanmar 3HM35F and Ample power recommended I go no larger than that because of the load on the water pump bearings. I originally installed it with one belt and frayed the belt all over the engine compartment because of the limited contact area at the alternator.
I changed the installation to double belts (had pulleys made at a local machine shop) in 1995 and it has run perfectly ever since. I still am using the same belts.

Good Luck

Joe S

 

[Ross]

If is or were posible I think I would favor separate belts for alternator and water pump. The "v" pulley on the crank could have 3 gooves one for the water pump and two for the alternator. It was done on automobile engines for years.

 

[Don12364]

Alternator Horsepower Requirements

In a previous existence I was IC a team who developed an alternator for Alfa Romeo's "Alfa Sud" car. The design was to generate 35amps at fast tick over - just like the unit subject of this thread except that it is designed to do 100 amps.
We ran this unit on a Heenan & Froude brake and were alarmed that at max engine revs it absorbed over 6 BHP from the engine. Alfa asked us to reduce the output power because their small engine did not have enough in reserve to pull the alternator AND the car! Problem was the design was optimised for tick over revs and the silly thing wanted to generate 48 volts at max engine speed. Factor this into Scotty's posting to see the true effect. In this case the power could be a large chunk of available engine power.
I guess the same mathematics also applies to a high output set up on a boat. When your batteries are low you may not have the engine performance to run the boat into a head sea - and you can't turn the alternator off in most set ups.

 

[Ross]

Re: Alternator Horsepower Requirements

Isn't that what a voltage regulator is supposed to control?